Toe iron for safety ski bindings

ABSTRACT

Two levers are pivoted to a toe iron part that is fixed to the ski and at their free ends carry respective sole-holders and are biased by a spring element toward their normal position. Each lever forms a crank of a slider crank mechanism. These two slider crank mechanisms have a common slider, which is guided in an at least approximately T-shaped cam slot that is fixed to the ski and has a stem which extends in the longitudinal direction of the ski. The spring element extends in the longitudinal direction of the ski and acts on the slider of the slider crank mechanisms.

O Umted States Patent 1 1111 3,744,810 J g nd 1 1 July 10, 1973 TOE IRON FOR SAFETY SKI BINDINGS 3,584,891 6/1971 Khazzam 280/1 1.35 T 3,194,574 7/1965 Bey] 280/ll.35 T [75] Invent Jmlkindi Falchami 3,232,631 2/1966 Witschard 280/1 1.35 T

Germany [73] Assignee: l-lannes Marker, Primary Examiner-Leo Friaglia Garmisch-Partenkirchen, Germany Assistant Examiner-Robert R. Song [22] Filed: p 7 1971 Attorney-Flat, Glpple & Jacobson [21] Appl. No.: 131,977 57 ABSTRACT Two levers are pivoted to a toe iron part that is fixed [30] Foreign Application Priority Data to the ski and at their free ends carry respective sole- Apr. 14, 1970 Germany P 20 17 849.9 holders and are biased y a Spring element toward their normal position. Each lever forms a crank of a slider [52] 11.8. CI .Q 280/l1.35 T crank mechanism These two slider crank mechanisms 51 1111. c1. A63c 9/00 have a common Slider, which is guided in an at least p- [58] Field of Search 280/11.35 T proximately p cam Slot that is fixed t9 the ski and has a stem which extends in the longitudinal direc- [56] References it d tion of the ski. The spring element extends in the longi- UNITED STATES PATENTS tudinal direction of the ski and acts on the slider of the 3,638,959 2/1972 Reuge 280/11.3s T Shder crank mechamsms' 3,603,607 7 Claims, 7 Drawing Figures 9/1971 Marker 280/ll.35 T

PATENIEU JUL 1 0 I973 sum 1' nr 3 lNVliN'I'URI Roland Jungkinc 1w; W

PATENTELJUL 1 01m SHEET 3 [IF 3 TOE IRON FOR SAFETY SKI BINDINGS This invention relates to a toe iron for safety ski bindings, which toe iron comprises two levers, which are pivoted to a toe iron portion that is fixed to the ski and which at their free ends carry respective soleholders and are biased by a spring element toward their normal position.

Compared to the so-called ball detent toe irons, these known toe irons have the advantage that they move through an elastic range before releasing the skiing boot so that they are not susceptible to shock. On the other hand, these toe irons have the important disadvantage that the force which is to be overcome for a release progressively increases beyond the required elastic range so that the skiing boot must be virtually squeezed out of the binding. As a result, these toe irons lack an exactly defined release position and the skiing boot which is fully loaded by the spring force moves also relative to the soleholder during its outward pivotal movement. If the force acting on the boot decreases before it has been released, it is generally impossible to compensate said relative movement so that the skiing boot will not return to its initial position but will remain on the ski in an angular position, in which a reliable and exact control of the ski is rendered difficult and atypical skiing injuries may result if the toe iron subsequently releases the boot unexpectedly and for no apparent reason.

Another disadvantage of these known toe irons resides in that the force required for a release depends also on the shape of the skiing boot. Because a skiing boot is normally not entirely symmetric, the different forces are required for a release of the boot by the toe iron to one side and the other so that the binding cannot be exactly adjusted and there are different margins of safety for twisting falls in different senses.

It is an object of the present invention so to improve and design a toe iron of the kind defined first hereinbefore that the disadvantages of the known toe irons of this kind are avoided in a simple manner.

In a toe iron for safety ski bindings, which toe iron comprises two levers, which are pivoted to a toe iron part that is fixed to the ski and which at their free ends carry respective soleholders and are biased by a spring element toward their normal position, the above object is accomplished according to the invention in that each lever forms a crank of a slider crank mechanism, these two slider crank mechanisms have a common slider, which is guided in an at least approximately T-shaped cam slot that is fixed to the ski and has a stem which extends in the longitudinal direction of the ski, and the spring element extends in the longitudinal direction of the ski and acts on the slider of the slider crank mechanisms. In this design, the elastic movement of the slider depends on the length of the stem of the cam slot, which stem extends in the longitudinal direction of the toe iron, and the spring element will not be stressed further or will be only slightly stressed further when the slider has completed said elastic movement and moves thereafter in those sections of the cam slot which are transverse to the longitudinal direction of the toe iron. During the latter movement, the wall surface of the cam slot which is fixed to the ski almost completely takes up the spring force so that there is virtually no resistance to the continued outward pivotal movement of the soleholders until the skiing boot is released. Contrary to the known toe irons of the kind defined first hereinbefore, the skiing boot need not be squeezed out of the binding and the forces required for a release of the boot to different sides do not unintendedly differ.

To minimize the friction between the soleholders and the skiing boot, freely rotatable backing rollers for the toe edge of the skiing boot may be provided in known manner on the soleholders. In a development of the invention, an arrangement has been found particularly desirable in which in the normal position of the levers the axes of rotation of the backing rollers are nearer to the longitudinal axis of the toe iron than the pivotal axes of the levers which carry the soleholders. In that case, an outward pivotal movement of the skiing boot causes the leading supporting roller to move along an are which is tangent to or intersects the arc of a circle which is at least approximately centered on the axis of rotation of the skiing boot on the ski. This ensures that the skiing boot cannot be displaced forwardly toward the tip of the ski during its elastic movement so that the toe iron and skiing boot can be automatically restored to their normal position without additional effort.

To minimize the structural expenditure, the axes of rotation of the backing rollers may be desirably coaxial with the axes on which the links of the slider crank mechanisms are pivoted to the cranks.

In a desirable embodiment of the structure of the toe iron according to the invention, the common slider of the slider crank mechanisms consists of a rotatably mounted guide roller. In this arrangement, the internal friction of the toe iron mechanism is much lower than where a slider moving with sliding friction is employed.

A particularly simple arrangement of the spring element will be enabled in that one end of the spring is directly secured to the slider of the slider crank mechanisms. In a development of the invention, however, the spring may act on the slider through the intermediary of a rocker lever. In this case, the toe iron may be much more compact because the spring may be arranged over the mechanism of the toe iron.

In that arrangement, an adjusting member is suitably provided, which is slidable in the direction of the longitudinal axis of the rocker lever, and the rocker lever is supported by said adjusting member on a toe iron portion that is fixed to the ski. In that arrangement, the adjusting member may be adjusted to change the fulcrum and lever ratio of the rocker lever so that the force required for a release of the toe iron may be changed without need to change the initial stress of the spring. As a result, the same optimum elastic range of the spring can always be utilized, regardless of the adjusted force required for a release. This is an important advantage.

Two embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which FIG. 1 is a top plan view showing the toe iron according to the invention in a normal position without the skiing boot. The housing has been removed to facilitate the understanding of the toe iron mechanism.

FIG. 2 is a central longitudinal sectional view showing the toe iron of FIG. I with the housing applied.

FIG. 3 is a top plan view showing the toe iron in its normal position with the inserted skiing boot and without the housing.

FIG. 4 is a top plan view showing the toe iron of FIG. 3 in a position at the end of the elastic range.

FIG. 5 is a top plan view showing the toe iron of FIG. 3 in a position after the release of the skiing boot.

FIG. 6 is a central longitudinal sectional view showing another embodiment of the toe iron according to the invention, and

FIG. 7 is a top plan view showing the toe iron of FIG. 6 in its normal position without a skiing boot and without a housing.

The toe iron which is shown in FIGS. 1 to 5 comprises a baseplate 1, which is adapted to be screwconnected to a ski and for this purpose is provided with four screw holes 2. Two vertically upwardly extending pivot pins 3 are secured to the baseplate. A channel section lever 4 is rotatably mounted on each pivot pin 3. The free ends of the levers 4 consist of soleholders 5, which can embrace the sole of the skiing boot (see particularly FIG. 3) at the top and laterally. That sole is indicated in the drawing only by dash-dot lines. By a pivot 7, a link 8 is pivoted to each lever 4. The other end of each link is pivoted to the axle 9 of a freely rotatable guide roller 10. Each lever 4'and link 8 together with the guide roller 10, which acts as a slider, form a slider crank mechanism, so that both mechanisms are coupled by the common guide roller 10. The guide roller 10 is guided in an approximately T-shaped cam slot 11, which is formed in the base plate 1 and has a stem extending in the longitudinal direction of the toe iron.

A U-shaped member 12 (see particularly FIG. 2) is mounted on the axle 9 of the guide roller 10 and forms an abutment for a helical tension spring 13, which extends in the longitudinal direction of the toe iron and at its other end is pivoted to a vertical pin 14, which is fixed to the baseplate. The helical tension spring 13 is preferably slightly prestressed and normally holds the toe iron mechanism in the position shown in FIG. 1, in

which the guide roller contacts the free end of the stem of the cam slot 11. It will be understood that a helical compression spring may also be used and involves a small structural expenditure.

The spring 13 may be replaced to change the force required for a release by the toe iron shown. Altematively, the forward end of the spring may be secured to an adjustable spring abutment, which is adjustable to vary the initial stress of the spring. This fixation of the forward end of the spring is known and not described more fully.

As an abutment for the toe edge of the skiing boot, a freely rotatable backing roller 15 is mounted on each of the pivots 7, which in the normal position of the toe iron are nearer to the central longitudinal axis of the toe iron than the pivot pins 3. As the skiing boot 6 is inserted into the binding, the boot can move forwardly between the soleholders 5 until the leading edge of the skiing boot engages the backing rollers 15. As a result, a slight outward pivotal movement is imparted to the soleholders 5 against the force of the spring 13, as is clearly apparent upon a comparison of FIGS. 1 and 3, so that the skiing boot 6 is automatically centered in its correct position.

For protection against mechanical damage from the outside, the toe iron mechanism is covered by a housing 16, e.g., of plastics material (see FIG. 2). The substantially U-shaped housing is placed over the toe iron mechanism and is secured to the baseplate by suitable means, which are not shown.

When a force which is outwardly directed transversely to the longitudinal direction of the ski acts on one of the soleholders, e.g., on the soleholder 5 which is shown on top in the drawings, and said force overcomes the initial stress of the helical tension spring 13, an outward pivotal movement about the pivot pin 3 will be imparted to that soleholder and owing to the cam slot 11 the guide roller 10 serving as a slider will be pulled rearwardly along a straight line by the associated link 8 to stress the spring. If the acting force acts only like a shock or if it is smaller than the set force required for a release, the spring will pull back the guide roller and the soleholders to their initial position when the force decreases. Because the previous outward pivotal movement involved a rearward pivotal movement of the leading backing roller 15 so as to prevent a forward movement of the skiing boot, there will be no large resistance opposing the return of the skiing boot to its normal position.

If a force which exceeds the set force required for a release acts on the soleholder 5 not only like a shock, the toe iron mechanism will first perform the movement described hereinbefore until the position shown in FIG. 4 has been reached. As the pivotal movement of the skiing boot and soleholder is continued, the guide roller enters the leading section of the T-shaped cam slot 11 which extends transversely to the longitudinal direction of the toe iron. That section is curved and its center of curvature lies in the longitudinal axis of the pin 14 so that the stress of the spring 13 is not increased during that movement. Besides, the force exerted by the spring is taken up by the wall surface of the cam slot 11, which is fixed relative to the ski so that the soleholder can continue its pivotal movement against almost no resistance until the skiing boot is completely released (see FIG. 5). The return of the toe iron to its normal position must be initiated by hand.

An automatic return of the toe iron to its normal position after the release of the skiing boot will be ensured if that portion of the T-shaped cam slot which extends transversely to the longitudinal direction of the ski has a slightly smaller curvature so that the stress of the spring 13 is increased during the outward pivotal movement of the toe iron and the amount of said stress increase is just sufficient to overcome the frictional resistance opposing the return of the toe iron to its initial position.

An adaptation of the toe iron to soles differing in thickness will be enabled if the entire toe iron mechanism and the cam slot can be vertically adjusted relative to the baseplate by means which are known and for this reason are not described more fully.

The toe iron shown in FIGS. 6 and 7 differs from the one described hereinbefore only by the different design of the spring mechanism. Like components are designated with the same reference characters.

In this embodiment, the spring element does not act directly on the guide roller 10 but a tie rod 20 (FIG. 6) which extends in the longitudinal direction of the toe iron is secured to the U-shaped member 12 which is mounted on the axle 9 of the guide roller 10. A channel member 21 extends at least approximately vertically upwardly and at one of its end faces is welded to the baseplate 1. The web 22 of said channel member 21 is formed with a slot 23, which is transverse to the longitudinal direction of the toe iron and through which the tie rod 20 extends. The leading end of the tie rod 20 is formed with a vertical bore. A screw 25 is articulatedly mounted in said bore and extends between the flanges of member 21. An adjusting member 26 is screwed on the screw 25 and by means of two lateral lugs (see FIG. 7) bears on the leading edges of the flanges of the channel member 21. The top end of the screw 25 is articulatedly mounted on another tie rod 27, which extends rearwardly through a bore 28 in the web 22 of member 21 and at its free end carries a disc 29, which is held by a circlip. That disc 29 serves as an abutment for a helical compression spring 30, which at its other end bears on the web 22 of member 21. The screw 25 is provided at its top end with a head 31, which facilitates a rotation of the screw to move the adjusting member 26 along the screw, which is held against axial movement.

The mode of operation of that spring mechanism is extremely simple. If a pivotal movement of the soleholders 5 results in a movement of the guide roller in the cam slot 11, the tie rod causes the screw 25, which forms a two-armed lever, to tilt about the points where the adjusting member 26 bears on the channel member 21. The resulting pivotal movement of the top end of the screw results in an axial displacement of the tie rod 27 so that the spring 31 is stressed or its stress is increased. Upon a decrease of the force acting on the soleholders 5, the spring returns the toe iron mechanism to its initial position in a sequence of operation which is opposite to that just described.

To set the desired force required for arelease, the screw 25 is turned so that the adjusting member 26 is moved upwardly or downwardly so that the fulcrum of the screw and the effective lengths of the lever arms are varied. In this way, the force required for a release of the toe iron may be adjusted without need to change the initial stress of thespring. Because the design of the toe iron is the same as in the preceding embodiment in other respects, there is no need to describe its function in more detail.

What is claimed is:

l. A toe iron for safety ski bindings comprising a toe iron part which is adapted to be fixed to a ski, two levers pivotally mounted to said toe iron part on opposite sides of the longitudinal axis of said toe iron, a soleholder carried by each of said levers and adapted to receive the sole of a skiing boot, a cam slot fixed relative to said ski and having a first portion extending in the forward longitudinal direction of said toe iron and a second portion extending generally transversely to the longitudinal axis of said toe iron, a slider adapted to move along said cam slot, means connecting said slider to each of said levers so as to form a slider crank mechanism which includes said levers, a spring element extending in the longitudinal direction of said toe iron and cooperating with said slider to urge said slider forward and into contact with said first portion of said cam slot when said crank mechanism and soleholders are in their normal position, said slider being moveable against the biasing action of said spring element from said first portion to said second portion of said cam slot during the outward pivotal movement of said soleholders to allow a release of said skiing boot.

2. The toe iron of claim 1 in which each of said soleholders comprises a backing roller adapted to contact the sole of a said skiing boot and which is rotatably mounted to said levers at a point which, in the normal position of said levers, is closer to the longitudinal axis of said toe iron than the point at which said levers are pivotally mounted to said toe iron.

3. The toe iron of claim 2 in which said means connecting said slider to each of said levers comprise mechanical links which form part of said slider crank mechanism and are pivotally connected to said levers and further in which the point at which said backing rollers are rotatably mounted is coaxial with the point at which said mechanical links are pivotally mounted to said levers.

4. The toe iron of claim 1 in which said slider is a guide roller rotatably mounted to said toe iron.

5. The toe iron of claim 1 in which said spring is at tached to said slider.

6. The toe iron of claim 1 in which a rocker lever is mounted to said toe iron and forms a mechanical connection between said spring and said slider.

7. The toe iron of claim 6 in which said toe iron further comprises a second toe iron part fixed relative to said ski and an adjusting member cooperating with said second toe iron part and with said rocker lever such that said rocker lever is adjustable along its longitudinal 

1. A toe iron for safety ski bindings comprising a toe iron part which is adapted to be fixed to a ski, two levers pivotally mounted to said toe iron part on opposite sides of the longitudinal axis of said toe iron, a soleholder carried by each of said levers and adapted to receive the sole of a skiing boot, a cam slot fixed relative to said ski and having a first portion extending in the forward longitudinal direction of said toe iron and a second portion extending generally transversely to the longitudinal axis of said toe iron, a slider adapted to move along said cam slot, means connecting said slider to each of said levers so as to form a slider crank mechanism which includes said levers, a spring element extending in the longitudinal direction of said toe iron and cooperating with said slider to urge said slider forward and into contact with said first portion of said cam slot when said crank mechanism and soleholders are in their normal position, said slider being moveable against the biasing action of said spring element from said first portion to said second portion of said cam slot during the outward pivotal movement of said soleholders to allow a release of said skiing boot.
 2. The toe iron of claim 1 in which each of said soleholders comprises a backing roller adapted to contact the sole of a said skiing boot and which is rotatably mounted to said levers at a point which, in the normal position of said levers, is closer to the longitudinal axis of said toe iron than the point at which said levers are pivotally mounted to said toe iron.
 3. The toe iron of claim 2 in which said means connecting said slider to each of said levers comprise mechanical links which form part of said slider crank mechanism and are pivotally connected to said levers and further in which the point at which said backing rollers are rotatably mounted is coaxial with the point at which said mechanical links are pivotally mounted to said levers.
 4. The toe iron of claim 1 in which said slider is a guide roller rotatably mounted to said toe iron.
 5. The toe iron of claim 1 in which said spring is attached to said slider.
 6. The toe iron of claim 1 in which a rocker lever is mounted to said toe iron and forms a mechanical connection between said spring and said slider.
 7. The toe iron of claim 6 in which said toe iron further comprises a second toe iron part fixed relative to said ski and an adjusting member cooperating with said second toe iron part and with said rocker lever such that said rocker lever is adjustable along its longitudinal axis. 